Comparison of the fraction of olfactory receptor pseudogenes in wolf (Canis lupus) with domestic dog (Canis familiaris)

Olfactory receptors（ORs）,the first dedicated molecules with which odorants physically interact to arouse an olfactory sensation,constitute the largest gene family in vertebrates.Dogs and wolves,like many other mammals,have a highly developed capability to detect and identify odorant molecules,even at minimum concentrations.In this study,the olfactory receptor repertoire from domestic dog and its closest relative,the wolf,were sequenced to estimate the fraction of pseudogenes in each subspecies.The fraction of disrupted olfactory receptor genes in dog was 17.78%,whereas,that in wolf was 12.08%.As expected the dog was less dependent on olfaction than the wolf,and the dog had more olfactory receptor pseudogenes.However,the observed difference between the two subspecies was not at the significant level（χ2 = 1.388,p = 0.239 0.05）.The values indicated that although domestication might play a role in the reduction of OR genes,it could not be concluded that the living environment provided by domestication lead to a significant reduction of the functional olfactory receptor repertoire.Furthermore,the purpose of domestication may also have influence on the ratio of functional olfactory receptor genes reduction.

Genetic Advances in Genome and Phenotypic Characters of Domestic Dog

Dogs represent such a rich potential resource to further understand diseases and genetic traits.Comparing the genomes of three species of canine,human,and rat in terms of genome analysis,it is found that dogs are highly conservative with humans and rats.The special population structure of dogs makes it a good model for studying the diversity of morphology and behavior,the genetic basis of mammalian evolution,and dis-eases.This article gives a brief review of recent advances in domestic dog origin and evolution,genomic structure,genetic variation in dog pheno-typic characteristics,and gene mapping.These research results are expected to provide a better theoretical basis for canine genetic breeding re-search and provide new ideas and methods for the prevention,diagnosis and treatment of human diseases.

Estimating the prevalence of Echinococcus in domestic dogs in highly endemic for echinococcosis

Background:Cystic echinococcosis(CE)and alveolar echinococcosis(AE)are highly endemic in Xiji County of Ningxia Hui Autonomous Region(NHAR)in China where the control campaign based on dog de-worming with praziquantel has been undertaken over preceding decades.This study is to determine the current prevalence of Echinococcus granulosus and E.multilocularis in domestic dogs and monitor the echinococcosis transmission dynamics.Methods:Study villages were selected using landscape patterns(Geographic Information System,GIS)for Echinococcus transmission“hot spots”,combined with hospital records identifying risk areas for AE and CE.A survey of 750 domestic dogs,including copro-sampling and owner questionnaires,from 25 selected villages,was undertaken in 2012.A copro-multiplex PCR assay was used for the specific diagnosis of E.granulosus and E.multilocularis in the dogs.Data analysis,using IBM SPSS Statistics,was undertaken,to compare the prevalence of the two Echinococcus spp.in dogs between four geographical areas of Xiji by theχ^(2)test.Univariate analysis of the combinations of outcomes from the questionnaire and copro-PCR assay data was carried out to determine the significant risk factors for dog infection.Results:The highest de-worming rate of 84.0%was found in the northwest area of Xiji County,and significant differences(P<0.05)in the de-worming rates among dogs from the four geographical areas of Xiji were detected.The highest prevalence(19.7%,59/300)of E.multilocularis occurred in northwest Xiji,though the highest prevalence(18.1%,38/210)of E.granulosus occurred in southwest Xiji.There was no significant difference(P>0.05)in the prevalence of E.granulosus in dogs from the northwest,southwest,northeast,and southeast of Xiji,but there were significant differences(P<0.05)between dogs infected with E.multilocularis from the four areas.None of the other independent variables was statistically significant.Conclusions:The results from this study indicate a high prevalence of both E.granulosus and E.muiltilocularis in dogs in Xiji County,NHAR.Transmission of E.multilocularis was more impacted by geographical risk-factors in Xiji County than that of E.granulosus.Dogs have the potential to maintain the transmission of both species of Echinococcus within local Xiji communities,and the current praziquantel dosing of dogs appears to be ineffective or poorly implemented in this area.

THE FIRST REPORT OF ECHINOCOCCUS MULTILOCULARIS IN DOMESTIC DOGS IN ZHANG COUNTY OF GANSU PROVINCE

In Zhang County of Gansu Province, 13 human cases of alveolar hydatid disease were reported up to 1990. However, the causative organism has not yet been described in animal hosts. In July 1990, postmortem examinations were made on 59 dogs (Canis familiaris) from the Caotan region of Zhang County. Of them, 6 were found to be infected with the adult worms of Echinococcus multilocularis. The morphological characteristics of the adult were compared in detail with those reported from different parts of China. Our adult specimens were closely resembling those of E. multilocularis reported from Ningxia. The role of domestic dogs in the epidemiology of alveolar echinococcosis in Zhang County was discussed.

Origin and phylogenetic analysis of Tibetan Mastiff based on the mitochondrial DNA sequence

At present, the Tibetan Mastiff is the oldest and most ferocious dog in the world. However, the origin of the Tibetan Mastiff and its phylogenetic relationship with other large breed dogs such as Saint Bernard are unclear. In this study, the primers were designed accord- ing to the mitochondrial genome sequence of the domestic dog, and the 2,525 bp mitochondrial sequence, containing the whole sequence of Cytochrome b, tRNA-Thr, tRNA-Pro, and control region of the Tibetan Mastiff, was obtained. Using grey wolves and coyotes as out- groups, the Tibetan Mastiff and 12 breeds of domestic dogs were analyzed in phylogenesis. Tibetan Mastiff, domestic dog breeds, and grey wolves were clustered into a group and coyotes were clustered in a group separately. This indicated that the Tibetan Mastiff and the other domestic dogs originated from the grey wolf, and the Tibetan Mastiff belonged to Carnivora, Canidae, Canis, Canis lupus, Canis lupus familiaris on the animal taxonomy. In domestic dogs, the middle and small breed dogs were clustered at first; German Sheepdog, Swedish Elkhound, and Black Russian Terrier were clustered into one group, and the Tibetan Mastiff, Old English Sheepdog, Leonberger, and Saint Bernard were clustered in another group. This confirmed the viewpoint that many of the famous large breed dogs worldwide such as Saint Bernard possibly had the blood lineage of the Tibetan Mastiff, based on the molecular data. According to the substitution rate, we concluded that the approximate divergence time between Tibetan Mastiff and grey wolf was 58,000 years before the present （YBP）, and the approximate divergence time between other domestic dogs and grey wolf was 42,000 YBP, demonstrating that the time of origin of the Tibetan Mastiff was earlier than that of the other domestic dogs.